Association of vitamin D gene polymorphisms in children with asthma - A systematic review

Association of polymorphisms of vitamin D gene in children with asthma and allergic rhinitis - Hospital based study

Vitamin D gene polymorphisms are known to be associated with asthma and allergic rhinitis in children. However, the genetic association of the same in South Indian children with above condition is still unknown. The present study was designed with the objective to analyze the association of polymorphisms of vitamin D receptor gene (VDR) (rs797532, rs154410, rs2258470, rs731236) and transport gene of vitamin D (rs7041) in children with asthma and allergic rhinitis in South India. Children (1-18years) presenting with symptoms suggestive of asthma and allergic rhinitis to hospital based outpatient department, in Vellore, South India were recruited as cases and children presenting with minor illness without respiratory complaints were enrolled as controls during January 2018 to September 2021. Polymorphisms were genotyped using tetra-arms PCR. Significant increase in levels of absolute eosinophil counts and serum IgE levels with decrease in vitamin D levels was seen among the cases. Significant association between levels of vitamin D and serum IgE was also observed. Analysis of polymorphisms showed that, in comparison to homozygous major allele the odds of having heterozygous (OR0.55 (0.3, 0.99) and homozygous minor form (OR0.52 (0.28, 0.97) of rs7975232, homozygous minor (OR 0.51 (0.34, 0.76)) and alternate allele (OR 0.7 (0.53, 0.93)) of rs154410 and homozygous minor form (OR 0.57 (0.37, 0.88) of rs731236 was significantly lesser among the cases. Genotypic model of rs154410 (p0.023) and allele form of rs7041 (p 0.041) were significantly associated with vitamin D levels however no association of gene blocks with cases was seen in haplotype analysis. There was an apparent gene pool difference noted in comparative analysis between Indian studies. The study is the first in south India to analyze levels of serum IgE, Vitamin D levels, association of VDR polymorphisms, and rs7041 in children with asthma.

Association between Single Nucleotide Polymorphisms Related to Vitamin D Metabolism and the Risk of Developing Asthma

Asthma is a chronic non-communicable disease that affects all age groups. The main challenge this condition poses is its heterogeneity. The role of vitamin D in asthma has aroused great interest, correlating low vitamin D levels and polymorphisms in the genes involved in its metabolic pathway with the risk of asthma. The aim of this study was to evaluate the influence of 13 single nucleotide polymorphisms (SNPs) related to the vitamin D metabolism on the susceptibility to asthma. An observational case-control study was performed, including 221 patients with asthma and 442 controls of Caucasian origin from southern Spain. The SNPs CYP24A1 (rs6068816, rs4809957), CYP27B1 (rs10877012, rs4646536, rs703842, rs3782130), GC (rs7041), CYP2R1 (rs10741657) and VDR (ApaI, BsmI, FokI, Cdx2, TaqI) were analyzed by real-time PCR, using TaqMan probes. The logistic regression model adjusted for body mass index revealed that in the genotype model, carriers of the Cdx2 rs11568820-AA genotype were associated with a higher risk of developing asthma (p = 0.005; OR = 2.73; 95% CI = 1.36-5.67; AA vs. GG). This association was maintained in the recessive model (p = 0.004). The haplotype analysis revealed an association between the ACTATGG haplotype and higher risk of asthma for the rs1544410, rs7975232, rs731236, rs4646536, rs703842, rs3782130 and rs10877012 genetic polymorphisms (p = 0.039). The other SNPs showed no effect on risk of developing asthma. The Cdx2 polymorphism was significantly associated with the susceptibility of asthma and could substantially act as a predictive biomarker of the disease.

Vitamin D Receptor Gene Polymorphisms and Risk of Atopic Dermatitis in Chinese Han Population

BACKGROUND

Studies investigated the associations between four Vitamin D receptor (VDR) common variations and interactions of gene-environment factors and atopic dermatitis (AD) in Chinese population are few.

METHODS

In this case-control study, 400 AD patients and 400 controls were genotyped for the FokI, TaqI, BsmI and ApalI variations of VDR genes by restriction fragment length polymorphism analysis. The associations between VDR genes and AD were assessed by univariate and multivariate logistic regression. The interactions between VDR genes and some risk factors were also explored using cross-over analysis. The corresponding odds ratio (ORs) and 95% confidence intervals (CI) were also calculated.

RESULTS

The FoKI rs2228570 polymorphism was significantly associated with an increased risk of atopic dermatitis in the co-dominant model (OR=2.93, 95% CI: 1.78-4.82. P=0.000), recessive model (OR=2.67, 95% CI: 1.68-4.26, P=0.000) and dominant model (OR=1.38, 95% CI: 1.04-1.84, P=0.028), and allele model. No significant associations were found among TaqI, BsmI and ApalI polymorphism and AD. The C-A-T-C and C-G-T-T haplotypes significantly increased the risk of atopic dermatitis. For rs2228570, the increased effects were more evident in the subgroups of age ≤8-month, cow milk and mixed, and keeping pet. Interactions between rs2228570 gene polymorphism and family history, age >8, and keeping pet increased the AD risk. The rs2228570 C allele decreased the relative mRNA expression.

CONCLUSION

The FokI rs2228570 C allele of VDR gene could be a risk candidate gene for AD. Interactions between FokI polymorphism and family history and some behaviors may increase the risk of AD.